While the movement of human resources has been activated lately in the midst of ongoing international exchanges, the importance of a passport where personal information is recorded has been growing. In particular, a passport has been playing a role as a so-called identification (identification card or the like) issued by a country, which is an official body and has reliability.
In particular, since the September 11th terrorist attacks, in order to tighten up immigration and departure control of each country, ICAO (International Civil Aviation Organization), which is a specialized agency of the United Nations, established a standard, and the work for introducing electronic passports has been started. Since it is important to inhibit forgery in the work, a technique of laser-marking personal names, symbols, letters, photographs, and the like has been drawing attention.
By the way, since an electronic passport can identify an individual, if personal information can easily be falsified or faked, the reliability on the identification falls, and it may pose a problem for the development of international exchanges or worldwide movement of human resources.
Therefore, how to inhibit falsification and forgery in the aforementioned electronic passport is an important problem. Since the electronic passport has a light, thin, short, and small standard, how to clearly display personal names, symbols, letters, photographs, and the like with high contrasts is important. Further, since realization of clear display with high contrasts leads to previous inhibition of falsification and forgery, the market expectation is great.
For such problems, attention is paid to a technique of laser-marking personal names, symbols, letters, photographs, and the like, specifically, a multilayer sheet for laser marking. For example, there are the following Patent Documents 1 and 2.
Patent Document 1 discloses a laser-marking multilayer sheet which is a multilayer sheet having at least a surface layer and an internal layer and formed by subjecting (A) a surface layer of a transparent thermoplastic resin and (B) an internal layer of a thermoplastic resin composition containing 0.01 to 5 parts by weight of an energy absorber absorbing a (b-2) laser beam and 0.5 to 7 parts by weight of a (b-3) colorant with respect to 100 parts by weight of a (b-1) thermoplastic resin to melt coextrusion for the purpose of obtaining a multilayer sheet having no damage in appearance, good contrasts, and excellent surface flatness and smoothness and being capable of laser marking.
Patent Document 2 discloses a laser-marking multilayer sheet which is a multilayer sheet having at least the first surface layer/an internal layer/and the second surface layer and formed of (A) the first and the second transparent surface layers of a thermoplastic resin composition containing 0.001 to 5 parts by weight of mica and/or carbon black with respect to 100 parts by weight of a transparent thermoplastic resin and (B) an internal layer of a thermoplastic resin composition containing 0.001 to 3 parts by weight of an energy absorber absorbing a laser beam with respect to 100 parts by weight of a thermoplastic resin with a composition ratio of the first surface layer/internal layer/the second layer of 1:4:1 to 1:10:1 and formed by subjecting the first surface layer/the internal layer/the second surface layer to melt coextrusion for the purpose of obtaining a multilayer sheet having no damage in appearance, good contrasts, and excellent surface flatness and smoothness and being capable of laser marking.
For certain, since each of the laser-marking multilayer sheets in Patent Documents 1 and 2 has excellent thermal adhesiveness with these multilayer sheets or, for example, with a thermoplastic resin sheet such as a PETG sheet or an ABS resin sheet and can obtain sufficient printability for printing letters and numbers by laser marking by laser beam irradiation, it deserves recognition. However, there is a problem of insufficient drawing of an image of a person's face or the like as a passport as a so-called identification. That is, a sufficient response to how to display personal information such as a personal name, symbols, letters, a photograph, and the like clearly in a light, thin, short, and small standard is not shown.